Theoretically, since an anime convention is typically a ticketed event, any convention can be a clothing-optional area. By purchasing a ticket you are consenting to enter an area where nudity is allowed. But no anime conventions that I know of does this.

I simply want to cosplay a naked anime character. Doesn't matter which one because they're naked.
Don't hate on my cosplay idea ok?

Well, first things first when planning on attending any anime con, check the local rules. Many cons have restrictions, even strange ones - such as no metal weapons (if you buy a sword from one of the dealers, you'll have to bring it back to your hotel room in its box - unboxing within the con area can get you kicked out), for example. Most have no-shirt-no-shoes-no-service type rules, or "this is a family friendly environment, and you may be told to leave based on your outfit" as a more general issue. Nearly all require genital coverings of some kind at the very least.

So, with no outfit at all, I'm expecting most US cons would tell you to leave right away, if the police aren't called on you first.

If you go in a flesh tone body suit, that may be an exception. If you want to go that angle, be sure to use underwear (and, for the guys, a dance belt) underneath, and make it a character like a Titan, not just going as "nude human", which isn't a character and may get you kicked out for similar reasons as above.

I simply want to cosplay a naked anime character. Doesn't matter which one because they're naked.
Don't hate on my cosplay idea ok?

Well, first things first when planning on attending any anime con, check the local rules. Many cons have restrictions, even strange ones - such as no metal weapons (if you buy a sword from one of the dealers, you'll have to bring it back to your hotel room in its box - unboxing within the con area can get you kicked out), for example. Most have no-shirt-no-shoes-no-service type rules, or "this is a family friendly environment, and you may be told to leave based on your outfit" as a more general issue. Nearly all require genital coverings of some kind at the very least.

So, with no outfit at all, I'm expecting most US cons would tell you to leave right away, if the police aren't called on you first.

If you go in a flesh tone body suit, that may be an exception. If you want to go that angle, be sure to use underwear (and, for the guys, a dance belt) underneath, and make it a character like a Titan, not just going as "nude human", which isn't a character and may get you kicked out for similar reasons as above.

Ok thanks, maybe I'll just do my cosplay at the clothing-optional beaches I'm going to this summer.